The present invention relates generally to a backup processing system for data processing systems executing on-line processing and batch processing, and more particularly to backup processing technology capable of preventing backup processing delays when trouble occurs during a backup operation.
On-line processing and batch processing in data processing systems of banks, securities firms, etc., sometimes terminate abruptly due to bugs in the programs, trouble with storage devices, etc., leaving data in an inconsistent state. Moreover, data are sometimes erased by human errors made during data processing. Several means are known for correcting the inconsistencies in such data, restarting the data processing or redoing such data processing from scratch. One means restores a data processing system by backing up data from time to time and restoring the data if trouble has occurred.
With the means for backing up and restoring data, data of a database system, for example, are regularly backed up to a storage medium such as magnetic tape. If trouble occurs in the database system, the data are restored from the magnetic tape to the database system storage device. The backup system dates back to an appropriate point in time to reconstruct the data in the storage device of the database system. Thus the data of the database system are restored so that processing can recommence.
In the case of batch processing, the data in the system's storage device are backed up on magnetic tape prior to batch processing. If batch processing comes to an irregular end, the data are restored from the magnetic tape to the storage device, and then batch processing is started again from scratch.
JP-A-242437/2000 discloses a storage-device system which makes a copy of data to be backed up in its storage device so that backup data can be made not from the data, but from the copy; therefore access to the data in the storage device is not disrupted even while the data are being backed up.
Sometimes, data are being backed up on magnetic tape, as described above, backup processing comes to an irregular end due to trouble with the magnetic tape drive or the magnetic tape. In this case, another magnetic tape drive and another magnetic tape must be readied, the data-backup processing must be redone from scratch, and backup processing takes a long time.
Recently, the amount of data input to data processing systems has burgeoned, increasing the amount of data which need to be backed up. In contrast, the time allocated for data-backup processing has been decreasing in order to minimize the effects of data-backup processing on on-line business affairs. If data-backup processing of a system ends irregularly, data-backup processing has to be redone from scratch. Thus data-backup processing takes much longer to be completed than the time allocated for such processing, and may affect on-line business affairs.
With the storage-device system of JP-A-242437/2000, the effects of irregular termination of backup processing on online business affairs can be lessened. However, if data-backup processing terminates irregularly, the back-up has to be redone from scratch; accordingly the data backup takes a long time to complete and the process ties up resources such as magnetic tape drives and data transfer routes for a long time.